#include "bits/stdc++.h"
using namespace std;
#ifdef _DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

#define int long long
#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define all(c) begin(c), end(c)
const int INF =
    sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}

template <class T, class... Tail>
void tied_sort(vector<T> &a, vector<Tail> &... tail) {
  int n = a.size();
  using S = tuple<T, Tail...>;
  vector<S> s(n);
  for (int i = 0; i < n; i++)
    s[i] = make_tuple(a[i], tail[i]...);
  sort(s.begin(), s.end());
  for (int i = 0; i < n; i++)
    tie(a[i], tail[i]...) = s[i];
}

signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  freopen("A-small-attempt1.in", "r", stdin);
  freopen("A-small-attempt1.txt", "w", stdout);
  // freopen("in.txt", "r", stdin);
  // freopen("out.txt", "w", stdout);
  int T;
  cin >> T;
  cout << fixed << setprecision(10);
  for (int t = 0; t < T; t++) {
    double D;
    int N;
    cin >> D >> N;
    if (N > 2)
      break;
    vector<double> K(N), S(N);
    rep(i, 0, N) { cin >> K[i] >> S[i]; }
    tied_sort(K, S);
    dump(K, S);
    double totaltime = 0;
    rep(i, 0, N - 1) {
      double mint = INF;
      int minid = -1;
      rep(j, 0, N - 1) {
        if (K[j] > D)
          break;
        if (S[i + 1] > S[i])
          continue;
        double time = (K[i + 1] - K[i]) / (S[i] - S[i + 1]);
        if (K[j] + S[j] * time > D)
          continue;
        if (chmin(mint, time)) {
          minid = j;
        }
      }
      if (minid == -1) {
        break;
      }
      rep(j, 0, N) { K[j] += S[j] * mint; }
      S[minid] = S[minid + 1];
      totaltime += mint;
    }
    double ans = 0;
    totaltime += (D - K[0]) / S[0];
    ans += D / totaltime;
    cout << "Case #" << t + 1 << ": " << ans << endl;
  }
  return 0;
}